Link adaptation for concurrent ofdma and non-ofdma signaling

ABSTRACT

Embodiments include methods for a network node configured to communicate with wireless devices via orthogonal frequency division multiple access (OFDMA) signaling and non-OFDMA signaling. Such methods include creating a frequency gap in the OFDMA signaling, with the frequency gap including one or more adjacent OFDM sub-carriers. Such methods include selecting a center frequency for the non-OFDMA signaling to be within the frequency gap and selecting one or more modulation and coding schemes (MCS) for the OFDMA signaling based on interference to the OFDMA signaling by the non-OFDMA signaling. Other embodiments include network nodes configured to perform such methods, and computer-readable media storing computer-executable instructions that embody such methods.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of and claims the benefit of priorityfrom U.S. patent application Ser. No. 16/344,482 filed on Apr. 24, 2019,which is a U.S. national-stage entry of international applicationPCT/EP2016/077155 filed on Nov. 9, 2016. The entire disclosures of theabove-mentioned applications are incorporated herein by reference forall purposes.

TECHNICAL FIELD

The present invention relates generally to the field of wirelesscommunication. More particularly, it relates to coexistence of OFDMA(orthogonal frequency division multiple access) signaling and non-OFDMAsignaling.

BACKGROUND

There are numerous scenarios where coexistence of OFDMA and non-OFDMAsignaling may be beneficial. Such a type of scenario, which will be usedherein as an illustrative example, is one where the concept of Internetof Things (IoT) is becoming prominent in wireless communication.

Internet of Things is expected to increase the number of connectedcommunication devices significantly. Many of these devices may typicallyoperate in unlicensed bands, for example, in the 2.4 GHz ISM(industrial, scientific and medical) band. Example communicationstandards that are expected to be prominent in IoT services areBluetooth Wireless Technology (hereinafter Bluetooth), in particularBluetooth Low Energy (BLE) and future versions of IEEE 802.11 like802.11ax. It can also be expected that future versions of IEEE 802.11may support more efficient narrow-band transmissions in order to allowfor lower cost implementations and more energy efficient communication,herein referred to as NB-WiFi. It can also be expected that such aNB-WiFi version would at least partly build on 802.11ax.

Supposedly, IoT applications typically require low data rate (smallamounts of data per transmission and/or scares transmissions). However,since the number of IoT devices may be extremely large, the aggregatedIoT data rate may still be substantial.

The typically required coverage range for IoT communication is expectedto be substantially less than that provided by cellular communicationsystems, while the coverage which can be obtained by e.g. conventionalBluetooth or 802.11b/g/n/ac may not suffice. Coverage may be increasedby reducing the data rate, which implies that a certain amount of datawill take longer time to transmit while occupying the communicationchannel This may lead to congestion if a large number of devices sharethe channel as is expected for IoT.

There is also a trend towards use of the unlicensed bands forcommunication services that are traditionally supported in licensedbands. For example, the third generation partnership project (3GPP) havedeveloped versions of their Long Term Evolution (LTE) standard, foroperation in the 5 GHz unlicensed band.

To obtain good performance for both IoT applications and non-IoTapplications, coordination of the communication may be beneficial.Coordination by time sharing of the channel may be inferior, since thedata rate is very low for the individual links in IoT, which may lead topoor spectrum efficiency.

The non-IoT communication may, typically, use OFDMA signaling. EP1798924 A1 discloses a solution where, for a first (OFDM) communicationsystem, carrier frequencies within a frequency range are temporarilydisabled to provide the frequency range for a second communicationsystem. A problem is that the first and second communication system mayinterfere with each other.

Therefore, there is a need for link adaptation approaches in scenarioswhere OFDMA signaling and non-OFDMA signaling coexist.

SUMMARY

It should be emphasized that the term “comprises/comprising” when usedin this specification is taken to specify the presence of statedfeatures, integers, steps, or components, but does not preclude thepresence or addition of one or more other features, integers, steps,components, or groups thereof.

It is an object of some embodiments to solve or mitigate at least someof the above or other disadvantages.

According to a first aspect, this is achieved by a link adaptationmethod of a network node. The network node is adapted to operate inconcurrent association with one or more orthogonal frequency divisionmultiple access (OFDMA) wireless communication devices using OFDMAsignaling, and a non-OFDMA wireless communication device using non-OFDMAsignaling. The non-OFDMA signaling has a bandwidth that is smaller thana maximum bandwidth of the OFDMA signaling.

The method comprises excluding one or more sub-carriers from the OFDMAsignaling to create a frequency gap and determining a center frequencyof the non-OFDMA signaling such that the center frequency is within thefrequency gap. The method also comprises selecting a modulation andcoding scheme to be used for the OFDMA signaling based on a firstsignal-to-interference value, wherein the non-OFDMA signaling acts asinterference to the OFDMA signaling.

The network node may, for example, be an access point (AP) adapted tooperate in accordance with IEEE 802.11 or another standard using OFDMAsignaling and in accordance with Bluetooth or another standard usingnon-OFDMA signaling. The OFDMA wireless communication devices may eachbe, for example, a user equipment (UE) or station (STA) adapted tooperate in accordance with IEEE 802.11 or another standard using OFDMAsignaling. The non-OFDMA wireless communication device may, for example,be a user equipment (UE) or station (STA) adapted to operate inaccordance with Bluetooth (e.g. BLE) or another standard using non-OFDMAsignaling.

The OFDMA signaling may, for example, be adapted to support data ratesin relation to each wireless communication device that are(substantially) higher than the data rates in relation to each wirelesscommunication device that the non-OFDMA signaling is adapted to support.

The non-OFDMA signaling may, for example, have a bandwidth that issubstantially smaller than the maximum bandwidth of the OFDMA signaling,e.g. less than or approximately equal to a tenth of the maximumbandwidth of the OFDMA signaling.

The created frequency gap may, for example, be approximately equal tothe bandwidth of the non-OFDMA signaling.

The sub-carriers to be excluded may, for example, be adjacentsub-carriers. For example, the sub-carriers to be excluded may be thoseof a (e.g. smallest) resource unit (RU) of the OFDMA signaling.

The center frequency may, for example, be determined to be(approximately) centered in the created frequency gap. Determining thecenter frequency of the non-OFDMA signaling to be within the createdfrequency gap may, for example, be achieved by frequency shifting eitheror both of the OFDMA signaling and the non-OFDMA signaling, if needed.

The selection of the modulation and coding scheme to be used for theOFDMA signaling may, for example, comprise (for a number of potentialmodulation and coding schemes) comparing the firstsignal-to-interference value with a signal-to-interference thresholdassociated with the potential modulation and coding scheme, andselecting one of the potential modulation and coding schemes for whichthe first signal-to-interference value is greater than the associatedsignal-to-interference threshold. For example, the selected modulationand coding schemes may be the one providing best capacity (and/or beingleast robust) among the potential modulation and coding schemes forwhich the first signal-to-interference value is greater than theassociated signal-to-interference thresholds.

In some embodiments, selecting the modulation and coding scheme to beused for the OFDMA signaling may comprise selecting a nominal modulationand coding scheme for the OFDMA signaling, and adjusting the modulationand coding scheme of sub-carriers adjacent to the frequency gap to amodulation and coding scheme that is more robust than the nominalmodulation and coding scheme. Adjacent may indicate directly adjacentonly or a collection (e.g. a resource unit) including the directlyadjacent.

Robustness of modulation and coding schemes may be defined in terms ofcoding rate, bits per symbol of the modulation, packet size, or acombination thereof. For example, a modulation and coding scheme may beconsidered more robust if it has lower coding rate and/or less bits persymbol than another modulation and coding scheme. A typicalcharacteristic of a more robust modulation and coding scheme may be thatit can be expected to achieve the same error rate as a less robustmodulation and coding scheme already for a smallersignal-to-interference-ratio (SIR).

According to some embodiments, the method may further comprise selectinga modulation and coding scheme to be used for the non-OFDMA signalingbased on a second signal-to-interference value, wherein the OFDMAsignaling acts as interference to the non-OFDMA signaling. The selectionof the modulation and coding scheme to be used for the non-OFDMAsignaling may, for example, comprise similar considerations as explainedabove for the selection of the modulation and coding scheme to be usedfor the OFDMA signaling. In some embodiments, the potential modulationand coding schemes be used for the non-OFDMA signaling may be differentmodes of Bluetooth communication.

In some embodiments wherein first and second transmission power levelsare for the OFDMA and non-OFDMA signaling, respectively, the method mayfurther comprise selecting at least one of the first and secondtransmission power level based on a first signal-to-interferencecondition, thereby adapting the first (and the second)signal-to-interference value.

Selection of the at least one of the first and second transmission powerlevel may, for example, comprise selecting at least one of the first andsecond transmission power level such that the firstsignal-to-interference value is greater than a minimumsignal-to-interference value associated with the OFDMA signaling (firstsignal-to-interference condition).

Additionally or alternatively, selection of the at least one of thefirst and second transmission power level may, for example, compriseselecting at least one of the first and second transmission power levelsuch that the second signal-to-interference value is greater than aminimum signal-to-interference value associated with the non-OFDMAsignaling.

According to some embodiments, the method may further comprise adaptingthe first (and the second) signal-to-interference value by selecting thenumber of the one or more excluded sub-carriers based on a secondsignal-to-interference condition.

Selection of the number of the one or more excluded sub-carriers may,for example, comprise selecting the number such that the worst casefirst signal-to-interference value is greater than a minimumsignal-to-interference value associated with the OFDMA signaling (secondsignal-to-interference condition).

The OFDMA and non-OFDMA signaling may, according to some embodiments,comprise downlink (DL) signals and the method may further compriseconcurrently transmitting the downlink signals.

Excluding the one or more sub-carriers from the OFDMA signaling maycomprise setting corresponding inputs of an inverse fast Fouriertransformer (IFFT) to zero.

The OFDMA and non-OFDMA signaling may, according to some embodiments,comprise uplink (UL) signals. Then, the method may further comprisesending (to the OFDMA wireless communication devices) respectivemessages indicative of the excluded sub-carriers and the selectedmodulation and coding scheme to be used for OFDMA signaling and sending(to the non-OFDMA wireless communication device) a message indicative ofthe center frequency.

Messages (the same as, or different from, the messages above) may alsoindicate other transmission parameters, such as one or more of selectedmodulation and coding scheme to be used for non-OFDMA signaling, firstand/or second transmission power levels, etc.

A message to an OFDMA wireless communication device indicatingsub-carriers to be used for uplink transmission, wherein thesub-carriers to be used do not comprise or overlap with the excludedsub-carriers, is intended to be an example of a message indicative ofthe excluded sub-carriers.

The method may, in some embodiments, further comprise concurrentlyreceiving the uplink signals from the OFDMA wireless communicationdevices and from the non-OFDMA wireless communication device, extractingthe OFDMA signaling by excluding the one or more sub-carriers from anOFDMA demodulated signal, and extracting the non-OFDMA signaling byfiltering. Exclusion of the one or more sub-carriers from the OFDMAdemodulated signal may typically comprise exclusion of sub-carrierscorresponding to the non-OFDMA signaling.

Excluding the one or more sub-carriers from the OFDMA demodulated signalmay comprise setting corresponding outputs of an IFFT to zero, or maycomprise ignoring corresponding outputs of the IFFT. Ignoring someoutputs of the IFFT may comprise not using the outputs in the OFDMAdemodulation.

A second aspect is a computer program product comprising a computerreadable medium, having thereon a computer program comprising programinstructions, the computer program being loadable into a data-processingunit and adapted to cause execution of the method according to the firstaspect when the computer program is run by the data-processing unit.

A third aspect is a link adaptation arrangement for a network node. Thenetwork node is adapted to operate in concurrent association with one ormore orthogonal frequency division multiple access (OFDMA) wirelesscommunication devices using OFDMA signaling, and a non-OFDMA wirelesscommunication device using non-OFDMA signaling. The non-OFDMA signalinghas a bandwidth that is smaller than a maximum bandwidth of the OFDMAsignaling.

The arrangement comprising a controller adapted to cause exclusion (e.g.by a frequency gap creator) of one or more sub-carriers from the OFDMAsignaling to create a frequency gap, determination (e.g. by a centerfrequency determiner) of a center frequency of the non-OFDMA signalingsuch that the center frequency is within the frequency gap, andselection (e.g. by a modulation and coding scheme selector) of amodulation and coding scheme to be used for the OFDMA signaling based ona first signal-to-interference value, wherein the non-OFDMA signalingacts as interference to the OFDMA signaling.

In some embodiments, the controller may be further adapted to causeselection (e.g. by the same or a different modulation and coding schemeselector) of a modulation and coding scheme to be used for the non-OFDMAsignaling based on a second signal-to-interference value, wherein theOFDMA signaling acts as interference to the non-OFDMA signaling.

According to some embodiments, wherein first and second transmissionpower levels are for the OFDMA and non-OFDMA signaling, respectively,the controller may be further adapted to cause selection (e.g. by apower level selector) of at least one of the first and secondtransmission power level based on a first signal-to-interferencecondition, thereby causing adaption of the first signal-to-interferencevalue.

According to some embodiments, the controller may be further adapted tocause adaption of the first signal-to-interference value by causingselection (e.g. by the frequency gap creator in combination with abandwidth selector) of the number of the one or more excludedsub-carriers based on a second signal-to-interference condition.

In some embodiments, wherein the OFDMA and non-OFDMA signaling comprisedownlink signals, the controller may be further adapted to causeconcurrent transmission (e.g. by a transmitter/transceiver) of thedownlink signals.

In some embodiments, wherein the OFDMA and non-OFDMA signaling compriseuplink signals, the controller may be further adapted to cause sending(to the OFDMA wireless communication devices, e.g. by atransmitter/transceiver) of respective messages indicative of theexcluded sub-carriers and the selected modulation and coding scheme, andsending (to the non-OFDMA wireless communication device, e.g. by atransmitter/transceiver) of a message indicative of the centerfrequency.

The controller may, according to some embodiments, be further adapted tocause concurrent reception (e.g. by a receiver/transceiver) of theuplink signals from the OFDMA wireless communication devices and fromthe non-OFDMA wireless communication device, extraction of the OFDMAsignaling by exclusion of the one or more sub-carriers from an OFDMAdemodulated signal and extraction of the non-OFDMA signaling byfiltering. Exclusion of the one or more sub-carriers from the OFDMAdemodulated signal may typically comprise exclusion of sub-carrierscorresponding to the non-OFDMA signaling.

A fourth aspect is a network node comprising the arrangement accordingto the third aspect.

In some embodiments, any of the above aspects may additionally havefeatures identical with or corresponding to any of the various featuresas explained above for any of the other aspects.

An advantage of some embodiments is that coexistence of OFDMA signalingand non-OFDMA signaling is enabled.

Another advantage of some embodiments is that time division is avoided.

BRIEF DESCRIPTION OF THE DRAWINGS

Further objects, features and advantages will appear from the followingdetailed description of embodiments, with reference being made to theaccompanying drawings, in which:

FIG. 1 is a schematic drawing illustrating an example scenario wheresome embodiments may be applicable;

FIG. 2 is a flowchart illustrating example method steps according tosome embodiments;

FIG. 3 is a schematic illustration of OFDMA signaling that may berelevant in relation to some embodiments;

FIG. 4 is a schematic block diagram illustrating an example arrangementaccording to some embodiments;

FIG. 5 is a schematic block diagram illustrating example transmitter andreceiver arrangements according to some embodiments; and

FIG. 6 is a schematic drawing illustrating a computer readable mediumaccording to some embodiments.

DETAILED DESCRIPTION

Embodiments described herein enable an IoT system (typically with lowdata rate) and a non-IoT system (typically with high data rate) tooperate concurrently by having the non-IoT system use OFDMA, assigningone or more sub-carriers to the IoT system, and using the remainingsub-carriers for the non-IoT system. An advantage with this approach isthat the amount of sub-carriers allocated to the IoT system may berather flexible.

Using OFDM is conceptually simple and is already the approach used ine.g. IEEE802.11ah, which is a standard developed to be used below 1 GHz.However, OFDM is probably not a good choice for IoT communication sinceparameters such as, e.g., power consumption, cost, and simplicity ofimplementation are particularly important in many IoT devices.Therefore, a more appropriate choice for IoT communication may, forexample, be Gaussian Frequency Shift Keying (GFSK) as used in BLE.

Embodiments provide an approach to combining two different physicallayers (PHY) where one PHY is intended for high data rate communications(using OFDMA) and the other PHY is intended for low data ratecommunications (using non-OFDMA, e.g. IoT communication). The signals ofthe two PHY:s may not be perfectly orthogonal to one another. Hence, inorder to ensure proper operation for both types of signals, interferencebetween the two PHY:s should preferably be taken into account whenselecting transmission parameters such as, e.g., modulation and codingschemes and transmission power levels.

In the following, embodiments will be described where at least one of alink (or a plurality of links) used for OFDMA and a link used fornon-OFDMA are adapted to accommodate concurrent OFDMA and non-OFDMAoperation in a frequency efficient manner The (joint) link adaptation(LA) may comprise adaptation of one or more of the modulation and codingscheme, the transmission power level, and the frequency allocation forone or more of the links involved.

FIG. 1 illustrates an example scenario where some embodiments may beapplicable. In the example scenario a network node (NWN) 100 is adaptedto operate in concurrent association with one or more OFDMA wirelesscommunication devices 120 using OFDMA and a non-OFDMA wirelesscommunication device 110 using non-OFDMA. The non-OFDMA signal typicallyhas a bandwidth that is smaller than a maximum bandwidth of the OFDMAsignal. The OFDMA signal may, for example, be in accordance with an IEEE802.11 standard (e.g. IEEE 802.11ax) and the non-OFDMA signal may, forexample, be in accordance with a Bluetooth standard (e.g. Bluetooth LowEnergy—BLE).

FIG. 2 illustrates an example method 200 according to some embodiments.The example method 200 may, for example, be performed in the networknode 100 of FIG. 1.

It is to be noted that various steps of the example method 200 may beoptional (as indicated by dashed boxes). Furthermore, it should be notedthat even though the various steps of the example method 200 aredescribed as performed in a certain order, this is not to be consideredas limiting. Contrarily, steps may be performed in another order whilestill falling under the scope of the claims. For example, step 250 maybe performed before step 240 and even before step 230; step 240 may beperformed before step 230; steps 210-250 (or a selection thereof) may beperformed iteratively; etc.

The method starts in step 210, where transmission power levels for thelinks involved are selected. In some embodiments, all links may havevariable transmission power levels, while in other embodiments, somelinks may have transmission power levels that are not varied in thecontext presented herein (although they may be otherwise variable).

The transmission power levels are selected based on asignal-to-interference condition. For example, the selection may be suchthat a resulting signal-to-interference value (wherein the non-OFDMAsignal acts as interference to the OFDMA signal) is greater than aminimum acceptable signal-to-interference value associated with theOFDMA signaling. Additionally or alternatively, the selection may besuch that a resulting signal-to-interference value (wherein the OFDMAsignal acts as interference to the non-OFDMA signal) is greater than aminimum acceptable signal-to-interference value associated with thenon-OFDMA signal.

In step 220, a number of sub-carriers of the OFDMA signal are selected,which sub-carriers are excluded from OFDMA signal in step 230, whereby afrequency gap is created in the OFDMA signal. The frequency gap is foraccommodating the non-OFDMA signal, and in step 240 a center frequencyof the non-OFDMA signal is determined such that the center frequency ofthe non-OFDMA signal is within (typically approximately centered in) thefrequency gap.

Typically, the number of the sub-carriers to exclude is based on thebandwidth of the non-OFDMA signal. For example, the sub-carriers to beexcluded may be those of a (e g smallest) resource unit (RU) of theOFDMA signal if the non-OFDMA signal can be accommodated therein andsub-carriers of more than one RU (or a larger RU) may be excluded if thebandwidth of the non-OFDMA signal so requires.

Selection of the number of the sub-carriers to exclude may implyadaption of signal-to-interference values of the OFDMA and the non-OFDMAsignals. Hence, the number may be selected based on one or moresignal-to-interference conditions in a similar manner as explained forthe transmission power level selection of step 210.

In some embodiments, the bandwidth of the non-OFDMA signal may bevariable. For example, a larger bandwidth may be used to be able toavoid a high transmission power level and/or to be able to use aparticular modulation and coding scheme. Then, the selection of step 220should preferably be correspondingly variable.

In step 250, the modulation and coding scheme to be used for the OFDMAsignal is selected. The selection is based on the signal-to-interferencevalue, wherein the non-OFDMA signal acts as interference to the OFDMAsignal.

The selection of the modulation and coding scheme to be used for theOFDMA signaling may, for example, comprise (for a number of potentialmodulation and coding schemes) comparing the signal-to-interferencevalue with a signal-to-interference threshold associated with thepotential modulation and coding scheme, and selecting one of thepotential modulation and coding schemes for which thesignal-to-interference value is greater than the associatedsignal-to-interference threshold.

Typically, the selected modulation and coding scheme to be used for theOFDMA signal comprises a nominal modulation and coding scheme for theOFDMA signal and an adjusted modulation and coding scheme for one ormore sub-carriers adjacent to (or close to) the frequency gap, where theadjusted modulation and coding scheme is more robust than the nominalmodulation and coding scheme.

The selection in step 250 may also include selecting a modulation andcoding scheme to be used for the non-OFDMA signal. This selection isbased on a signal-to-interference value, wherein the OFDMA signal actsas interference to the non-OFDMA signal in a similar manner as explainedabove for the selection of the modulation and coding scheme to be usedfor the OFDMA signal.

The coexistence of OFDMA and non-OFDMA may be relevant for uplink and/ordownlink communication.

For downlink communication, the method may further comprise concurrentlytransmitting the downlink OFDMA and non-OFDMA signals, as illustrated instep 260.

For uplink communication, the method may further comprise sendingindications regarding transmission parameters to the wirelesscommunication devices (WCD), as illustrated in step 270. Suchtransmission parameters may include a relevant selection of theparameters of one or more of steps 210, 220, 240 and 250. Typically, atleast the excluded sub-carriers (possibly in the form of an uplinkallocation not overlapping with the excluded sub-carriers) and theselected coding and modulation scheme may be indicated to the OFDMAwireless communication devices, and at least the center frequency may beindicated to the non-OFDMA wireless communication device.

For uplink communication, the method may further comprise concurrentlyreceiving the uplink signals from the OFDMA wireless communicationdevices and from the non-OFDMA wireless communication device (not shownin FIG. 2).

When the joint LA is performed for the downlink, the OFDMA and non-OFDMAsignals are transmitted from the network node, which is the same node asis coordinating the selection of parameters (modulation and codingschemes, transmission power levels, number of sub-carriers to exclude,etc.) for the link adaptation. The network node may, thus, decide how toadjust the parameters on the fly (e.g. on a packet-by-packet basis) andthe joint LA may be completely transparent to the receivers of thedownlink signals.

When the joint link LA is performed for the uplink, the selection ofparameters may (at least partly) be based on information from thenetwork node to the wireless communication devices (e.g. instructions)and/or vice versa (e.g. measurement reports). Thus, the joint LA willnot be completely transparent to the transmitters of the uplink signals.However, instructions from the network node do not have to convey thereason for the link adaptation instructions to the wirelesscommunication devices. Furthermore, it may be advantageous to selectparameters in uplink scenarios such that there are margins to a channelsituation where communications fail.

FIG. 3 schematically illustrates a typical partition of a frequencyspectrum for OFDMA signaling into resources units (RU:s) of differentsizes. The particular example shown in FIG. 3 may, for example, relateto 20 MHz allocation in IEEE 802.11ax (see e.g. IEEE P802.11 WirelessLANs, “Specification Framework for TGax”, doc.:IEEE 802.11-15/0132r8,September 2015, FIG. 11). According to this example, the frequencyspectrum may be used for a single RU 301; for two RU:s 311, 318; forfour RU:s 321, 323, 326, 328; or for eight RU:s 331, 332, 333, 334, 335,336, 337, 338. Pilot tones are represented as arrows 351-358 and361-368. In relation to the method described in connection with FIG. 2,RU 335 may be excluded from OFDMA signaling and used for non-OFDMAsignaling, for example.

FIG. 4 schematically illustrates an example arrangement 400 that may,for example, be adapted to perform the method described in connectionwith FIG. 2.

The arrangement 400 may be comprised in a network node adapted tooperate in concurrent association with one or more OFDMA wirelesscommunication devices using OFDMA and a non-OFDMA wireless communicationdevice using non-OFDMA. The non-OFDMA signal has a bandwidth that issmaller than a maximum bandwidth of the OFDMA signal.

The arrangement 400 comprises a controller (CNTR) 420 and may possiblyalso comprise a transmitter and/or a receiver (illustrated in FIG. 4 asa transceiver (TX/RX) 410). Furthermore, the controller 420 maycomprise, or be otherwise associated with, one or more of a modulationand coding scheme selector (MCS) 421, a power level selector (PLS) 422,a bandwidth selector (BW) 423, a frequency gap creator (FGC) 424, and acenter frequency determiner (CFD) 425.

The controller 420 may be adapted to cause execution of the steps asdescribed in connection to FIG. 2. Thus, the controller is adapted tocause exclusion of one or more sub-carriers from the OFDMA signaling tocreate a frequency gap (compare with step 230) and determination of acenter frequency of the non-OFDMA signaling such that the centerfrequency is within the frequency gap (compare with step 240). Theexclusion may be caused by the frequency gap creator 424 and thedetermination may be caused by the center frequency determiner 425.

The controller is also adapted to cause selection of a modulation andcoding scheme (compare with step 250) to be used for the OFDMA signalbased on a first signal-to-interference value, wherein the non-OFDMAsignal acts as interference to the OFDMA signal. In some embodiments,the controller may be further adapted to cause selection of a modulationand coding scheme (compare with step 250) to be used for the non-OFDMAsignal based on a second signal-to-interference value, wherein the OFDMAsignal acts as interference to the non-OFDMA signal. The selection(s) ofmodulation and coding scheme(s) may be caused by one or more modulationand coding scheme selectors 421.

The controller may also be adapted to cause selection of transmissionpower level for at least one of the OFDMA and non-OFDMA signals based ona first signal-to-interference condition (compare with step 210). Theselection of transmission power level(s) may be caused by the powerlevel selector 422.

According to some embodiments, the controller may be further adapted tocause selection of the number of the one or more excluded sub-carriersbased on a second signal-to-interference condition (compare with step220). The selection of the number may be caused by the frequency gapcreator in combination with the bandwidth selector 423.

When the OFDMA and non-OFDMA signals comprise downlink signals, thecontroller may be further adapted to cause concurrent transmission bythe transceiver 410 of the downlink signals (compare with step 260).

When the OFDMA and non-OFDMA signals comprise uplink signals, thecontroller may be further adapted to cause (compare with step 270)sending by the transceiver 410 to the OFDMA wireless communicationdevices of respective messages indicative of the excluded sub-carriersand the selected modulation and coding scheme, and sending by thetransceiver 410 to the non-OFDMA wireless communication device of amessage indicative of the center frequency. The controller may befurther adapted to cause concurrent reception by the transceiver 410 ofthe uplink signals from the OFDMA wireless communication devices andfrom the non-OFDMA wireless communication device, extraction of theOFDMA signal by exclusion of the one or more sub-carriers from annon-OFDMA demodulated signal, and extraction of the non-OFDMA signal byfiltering. Exclusion of the one or more sub-carriers from the OFDMAdemodulated signal may typically comprise exclusion of sub-carrierscorresponding to the non-OFDMA signaling.

FIG. 5 schematically illustrate example transmitter and receiverarrangements according to some embodiments. The arrangements of FIG. 5may, for example, be comprised in the transceiver 410 of FIG. 4 and maybe (at least partly) controlled by the controller 420 of FIG. 4.

In the example transmitter, one or more sub-carriers are excluded fromthe OFDMA signal by setting the corresponding inputs of an inverse fastFourier transformer (IFFT) 510 to zero. For example, the inputsindicated by 502 may be set to zero while the inputs indicated by 501,503 are treated as normally for OFDMA signaling (compare with the use ofthe frequencies of RU 335 in FIG. 3 for non-OFDMA signaling). Thesetting of some inputs of the IFFT 510 to zero may be caused by thefrequency gap creator 424 of FIG. 4.

The input 504 for the non-OFDMA signal is modulated in modulator (MOD)520 and frequency shifted by frequency shifter (FS) 525 such that itscenter frequency is within the frequency gap created by exclusion ofsub-carriers from OFDMA signal. The frequency shifter 525 may becontrolled by the center frequency determiner 425 of FIG. 4.

The output of the IFFT 510 is pre-appended with a cyclic prefix (CP)515, as is commonly known in the art, and combined with the non-OFDMAsignal by combiner 530 to a signal 500 for concurrent downlinktransmission. The combiner 530 may be controlled by the power levelselector 422 of FIG. 4, such that the signals are correspondinglyweighted before combined.

In the example receiver, uplink signals 550 from the OFDMA wirelesscommunication devices and from the non-OFDMA wireless communicationdevice are concurrently received.

Extraction of the OFDMA signal is achieved, after cyclical prefixremoval (CPR) 565, by exclusion of the one or more sub-carriers from theOFDMA demodulated signal, which is achieved by setting correspondingoutputs of an IFFT 560 to zero, or by ignoring corresponding outputs ofthe IFFT. For example, the outputs indicated by 552 (corresponding toinputs 502 of the transmitter) may be set to zero or ignored, while theoutputs indicated by 551, 553 are treated as normally for OFDMAsignaling. The setting of some outputs of the IFFT 560 to zero (or theignoring of some outputs) may be caused by the frequency gap creator 424of FIG. 4.

Extraction of the non-OFDMA signal 554 is achieved by filtering out therelevant frequency interval by filter (FILT) 574 and demodulating thefiltered signal in demodulator (DEM) 570. The demodulation may includeapplying the inverse of the frequency shift applied by frequency shifter525. The filter 574 may be controlled by the bandwidth selector 423 ofFIG. 4.

The modulation and coding scheme selector 421 of FIG. 4 may control oneor more of the modulator 520 and the demodulator 570. Alternatively oradditionally, the modulation and coding scheme selector 421 of FIG. 4may control the processing of OFDMA signals before input into the IFFT510 and after output from the IFFT 560.

The described embodiments and their equivalents may be realized insoftware or hardware or a combination thereof. They may be performed bygeneral-purpose circuits associated with or integral to a communicationdevice, such as digital signal processors (DSP), central processingunits (CPU), co-processor units, field-programmable gate arrays (FPGA)or other programmable hardware, or by specialized circuits such as forexample application-specific integrated circuits (ASIC). All such formsare contemplated to be within the scope of this disclosure.

Embodiments may appear within an electronic apparatus (such as a networknode) comprising arrangements/circuitry/logic or performing methodsaccording to any of the embodiments. The electronic apparatus may, forexample, be an access point.

According to some embodiments, a computer program product comprises acomputer readable medium such as, for example, a USB-stick, a plug-incard, an embedded drive, or a read-only memory (ROM) such as the CD-ROM600 illustrated in FIG. 6. The computer readable medium may have storedthereon a computer program comprising program instructions. The computerprogram may be loadable into a data-processing unit (PROC) 620, whichmay, for example, be comprised in a network node 610. When loaded intothe data-processing unit, the computer program may be stored in a memory(MEM) 630 associated with or integral to the data-processing unit.According to some embodiments, the computer program may, when loadedinto and run by the data-processing unit, cause execution of methodsteps according to, for example, the method shown in FIG. 2.

Reference has been made herein to various embodiments. However, a personskilled in the art would recognize numerous variations to the describedembodiments that would still fall within the scope of the claims. Forexample, the method embodiments described herein describes examplemethods through method steps being performed in a certain order.However, it is recognized that these sequences of events may take placein another order without departing from the scope of the claims.Furthermore, some method steps may be performed in parallel even thoughthey have been described as being performed in sequence.

In the same manner, it should be noted that in the description ofembodiments, the partition of functional blocks into particular units isby no means limiting. Contrarily, these partitions are merely examples.Functional blocks described herein as one unit may be split into two ormore units. In the same manner, functional blocks that are describedherein as being implemented as two or more units may be implemented as asingle unit without departing from the scope of the claims.

Hence, it should be understood that the details of the describedembodiments are merely for illustrative purpose and by no meanslimiting. Instead, all variations that fall within the range of theclaims are intended to be embraced therein.

1. A method for a network node configured to communicate with wirelessdevices via orthogonal frequency division multiple access (OFDMA)signaling and non-OFDMA signaling, the method comprising: creating afrequency gap in the OFDMA signaling, wherein the frequency gap includesone or more adjacent OFDM sub-carriers; selecting a center frequency forthe non-OFDMA signaling to be within the frequency gap; and selectingone or more modulation and coding schemes (MCS) for the OFDMA signalingbased on interference to the OFDMA signaling by the non-OFDMA signaling.2. The method of claim 1, wherein selecting the one or more MCS for theOFDMA signaling comprises: selecting a nominal MCS for the OFDMAsignaling; and adjusting the MCS of sub-carriers of the OFDMA signalingthat are adjacent to the frequency gap to an MCS that is more robustthan the nominal MCS.
 3. The method of claim 1, further comprisingselecting an MCS for the non-OFDMA signaling based on interference tothe non-OFDMA signaling by the OFDMA signaling.
 4. The method of claim1, further comprising selecting a size of the frequency gap such thatthe interference to the OFDMA signaling by the non-OFDMA signaling isnot greater than a minimum signal-to-interference value associated withthe OFDMA signaling.
 5. The method of claim 1, further comprisingconcurrently transmitting the OFDMA signaling and the non-OFDMAsignaling to wireless devices.
 6. The method of claim 5, wherein: theOFDMA signaling is transmitted at a first transmission power level; thenon-OFDMA signaling is transmitted at a second transmission power level;and the method further comprises selecting at least one of the first andsecond transmission power levels such that one or more of the followingapplies: the interference to the OFDMA signaling by the non-OFDMAsignaling is not greater than a minimum signal-to-interference valueassociated with the OFDMA signaling; and the interference to thenon-OFDMA signaling by the OFDMA signaling is not greater than a minimumsignal-to-interference value associated with the non-OFDMA signaling. 7.The method of claim 6, wherein creating a frequency gap in the OFDMAsignaling comprises setting to zero one or more inputs of an inversefast Fourier transformer (IFFT) that correspond to the respective one ormore adjacent subcarriers.
 8. The method of claim 1, further comprising:sending, to one or more first wireless devices, respective firstmessages indicating the frequency gap and the MCS selected for the OFDMAsignaling; and sending, to one or more second wireless devices,respective second messages indicating the center frequency.
 9. Themethod of claim 8, further comprising: concurrently receiving uplinksignals from the first and second wireless devices; extracting the OFDMAsignaling, from the one or more first wireless devices, based onexcluding the one or more adjacent sub-carriers of the frequency gapfrom the received uplink signals; and extracting the non-OFDMAsignaling, from the one or more second wireless devices, based onfiltering the received uplink signals.
 10. The method of claim 1,wherein the non-OFDMA signaling has a bandwidth that is smaller than amaximum bandwidth of the OFDMA signaling.
 11. A non-transitory,computer-readable medium storing computer program instructions that,when executed by a controller of a network node, configure the networknode to perform operations corresponding to the method of claim
 1. 12. Anetwork node configured to communicate with wireless devices viaorthogonal frequency division multiple access (OFDMA) signaling andnon-OFDMA signaling, the network node comprising: a transceiverconfigured to communicate with the wireless devices; and a controlleroperably coupled to the transceiver and configured to: create afrequency gap in the OFDMA signaling, wherein the frequency gap includesone or more adjacent 01-DM sub-carriers; select a center frequency forthe non-OFDMA signaling to be within the frequency gap; and select oneor more modulation and coding schemes (MCS) for the OFDMA signalingbased on interference to the OFDMA signaling by the non-OFDMA signaling.13. The network node of claim 12, wherein the controller is configuredto select the one or more MCS for the OFDMA signaling based on:selecting a nominal MCS for the OFDMA signaling; and adjusting the MCSof sub-carriers of the OFDMA signaling that are adjacent to thefrequency gap to an MCS that is more robust than the nominal MCS. 14.The network node of claim 12, further comprising selecting an MCS forthe non-OFDMA signaling based on interference to the non-OFDMA signalingby the OFDMA signaling.
 15. The network node of claim 12, wherein thecontroller is further configured to select a size of the frequency gapsuch that the interference to the OFDMA signaling by the non-OFDMAsignaling is not greater than a minimum signal-to-interference valueassociated with the OFDMA signaling
 16. The network node of claim 12,wherein the transceiver and the controller are configured toconcurrently transmit the OFDMA signaling and the non-OFDMA signaling towireless devices.
 17. The network node of claim 16, wherein: the OFDMAsignaling is transmitted at a first transmission power level; thenon-OFDMA signaling is transmitted at a second transmission power level;and the controller is further configured to select at least one of thefirst and second transmission power levels such that one or more of thefollowing applies: the interference to the OFDMA signaling by thenon-OFDMA signaling is not greater than a minimum signal-to-interferencevalue associated with the OFDMA signaling; and the interference to thenon-OFDMA signaling by the OFDMA signaling is not greater than a minimumsignal-to-interference value associated with the non-OFDMA signaling.18. The network node of claim 17, wherein the controller is configuredto create a frequency gap in the OFDMA signaling based on setting tozero one or more inputs of an inverse fast Fourier transformer (IFFT)that correspond to the respective one or more adjacent subcarriers. 19.The network node of claim 12, wherein the controller and the transceiverare further configured to: send, to one or more first wireless devices,respective first messages indicating the frequency gap and the MCSselected for the OFDMA signaling; and send, to one or more secondwireless devices, respective second messages indicating the centerfrequency.
 20. The network node of claim 19, wherein the controller andthe transceiver are further configured to: concurrently receive uplinksignals from the first and second wireless devices; extract the OFDMAsignaling, from the one or more first wireless devices, based onexcluding the one or more adjacent sub-carriers of the frequency gapfrom the received uplink signals; and extract the non-OFDMA signaling,from the one or more second wireless devices, based on filtering thereceived uplink signals.
 21. The network node of claim 12, wherein thenon-OFDMA signaling has a bandwidth that is smaller than a maximumbandwidth of the OFDMA signaling.